Levelling apparatus



May 28, 1968 R. D. c. BONE LEVELLING APPARATUS 2 SheetsSheet 1 Filed Oct. 14, 1965 y 3, 1968 R. D. c. BONE 3,385,263

LEVELLING APPARATUS I Filed Oct. 14, 1965 2 Sheets-Sheet 2 United States Patent 3,385,263 LEVELLING APPARATUS Ronald D. C. Bone, Upminster, Essex, England, assignor to Shandon Scientific Company Limited, London, England, a British company Filed Oct. 14, 1965, Ser. No. 496,060 Claims priority, application Great Britain, Aug. 13, 1965, 34,698/65 13 Claims. (Cl. 118-503) ABSTRACT OF THE DISCLOSURE A clamp type work-holder including a resilient bed whereby plates of varying thicknesses may be retained with their upper surfaces lying in a common plane and substantially completely exposed except for edge portions engaged by flanges of upper elements of the clamp, at least one of which elements is pivotally associated with a cam actuated, spring biased lever.

This invention concerns the application of surface coatings to plane surfaced plates and, whilst the invention is generally applicable to such purposes, the invention is particularly applicable to the coating of plates used in socalled thin-layer chromatography and will be discussed herein in relation to that application.

In thin-layer chromatography plates made of relatively inert material such as metal, glass or plastics are coated with a thin layer of a slurry which is subsequently dried to provide the coating material in which the chromatographic run is to be performed. A spot of a mixture to be analysed in placed on the dry coating close to one edge of the plate. This edge is then dipped in a liquid which is to provide the carrier for the chromatographic run.

During the run the carrier liquid travels through the coating by capillarity and past the spot. The different constituents of the spot dissolve in the carrier liquid and are carried thereby at different speeds through the coating, so that during the run the constituents of the spot are specially separated from one another and form, if coloured, visible marks which slowly travel away from the spot. After the run has been in operation for a suflicient time to separate the constituents of the spot, the coating is dried and the positions of the different markings on the coating are located either by being visually apparent or by making them visually apparent, for example, by dyeing them or by subjecting them to ultra-violet light so that they luminesce. Once the positions of the markings are known the constituents of the spot can be determined, for example by comparison with a calibration chromatograph run performed simultaneously and under the same conditions on a spot of known constituents.

Where two or more chromatographic runs are carried out simultaneously and one chromatogram has a spot of known constituents placed on it to calibrate the other chromatogram, it is naturally of importance that the coatings on the plates should have the same consistency and thickness if accurately comparable results are to be obtained.

Apparatus has been devised for coating several chromatographic plates in side-by-side relationship to provide identical coatings by placing the plates on the floor of a trough and running a container of wet coating material along the top surfaces of the plates so that a layer of the material is deposited on each plate. This arrangement is satisfactory if the plates are of identical thickness but if the thicknesses differ from one another then the coating applied to the thinner plates is non-uniform in thickness being in parts thicker than the coating applied to the thicker plates. To prevent this from happening the plates have to be individually selected and therefore consider- 3,385,263 Patented May 28, 1968 able care had to be taken in the production of such coating apparatus to ensure that all the plates supplied with the apparatus were of the same thickness within predetermined tolerances, usually 10.1 mm.

Apparatus which overcome these disadvantages of the prior art is described in our Patent No. 945,868, and in our co-pending application No. 43,173/ 63. Such apparatus holds chromatographic plates of differing thicknesses with their surfaces to which the coating is to be applied in coplanar relationship. This is preferably achieved by applying resilient pressure to the marginal edges of the undersides of the plates so that the top surfaces of the marginal edges are pressed against coplanar locating surfaces.

An object of this invention is the provision of improved apparatus for coating chromatographic plates of different thicknesses.

In accordance with one aspect of this invention apparatus for holding chromatographic plates of different thicknesses side-by-side with their top surfaces in coplanar relationship, comprises elongated support means on to which the plates to be coated are placed and providing resiliently yieldable surfaces beneath the marginal edges of the plates, a base frame carrying the support means and providing spaced non-yielding locating surfaces which are relatively movable towards and away from one another from first relative positions at which they lie in a common plane above respective marginal edges of the plates, to second relative positions at which the spacing between the non-yielding surfaces is greater than the spacing between said yielda'ble surfaces to allow the plates to be lifted individually from the apparatus after they have been coated, and a handle-operated mechanism for producing relative movement of the non-yielding locating surfaces and which is adapted, after having moved them to said first relative positions, to reduce the distance be tween the non-yielding surfaces and the yieldable surfaces whereby the marginal edges of the plates are resiliently pressed against the coplanar non-yielding surfaces so that the top surfaces of the plates are brought to said common plane in readiness for the application of a coating thereto.

The reduction of the distance between the non-yielding surfaces and the locating surfaces may be carried out by pressing the non-yielding locating surfaces downwards onto the marginal edges of the plates or by lifting the yieldable surfaces so that the top faces of the plates are raised against the coplanar non-yielding surfaces.

In accordance with a second aspect of the invention apparatus for holding chromatographic plates of different thicknesses side-by-side with their top surfaces in coplanar relationship, comprises elongated support means onto which the plates to be coated are placed and providing resiliently yieldable surfaces beneath opposite marginal edges of the plates, a base frame carrying the support means and providing spaced non-yielding locating surfaces which are relatively movable towards and away from one another from first relative positions at which they lie in a common plane above respective marginal edges of the plates, to second relative positions at which the spacing between the non-yielding surfaces is greater than the spacing between said yieldable surfaces to allow the plates to be lifted individually from the apparatus after they have been coated and a handle-operated mechanism for producing relative movement of the non-yielding surfaces and which is adapted, after having moved them to said first positions, to move the yieldable surfaces upwardly whereby the marginal edges of the plates are resiliently pressed [upwards against the coplanar nonyielding surfaces so that the top surfaces of the plates are brought to said common plane in readiness for the application of a coating thereto.

Preferably the support means providing the yielda'ble surfaces is in the form of a carrier which may be removed bodily from the frame for cleaning and which suitably is spanned by an easily-cleaned flexible sheet. Such an arrangement has the advantage that the slurry-coated plates may be individually lifted from the carrier or the carrier may, if desired, be lifted bodily from the frame whilst still carrying the plates having wet coatings applied to them.

The invention has the advantage that a single movement of a handle is utilized to perform both the operation of positioning the nonyielding locating surfaces over the marginal edges of the plates and reducing the distance between the locating surfaces and the plates so that the faces of the plates to be coated are brought into coplanar relationship.

Preferably at least one of the non-yielding locating surfaces forms part of a side member hinged to the base frame. The side member is conveniently in the form of an angle plate having an upright limb forming one side of the base frame, and a horizontal limb which is hinged at its edge to the frame. The handle-operated mechanism can then be arranged to move the hinged angle plate between two positions at one of which the non-yielding locating surface provided by the angle plate over-lies the carrier and is coplanar with the other non-yielding locating surface, and at the other position of which the angle plate is swung downwardly about the hinge so that its non-yielding locating surface lies to one side of the frame to allow individual plates or the carrier to be lifted from it. The carrier may be provided with cut-outs along one edge to facilitate removal of the plates from it.

Conveniently the handle is arranged to rotate cams beneath the carrier to raise and lower it beneath the level of the locating surfaces. Suitably resilient connectors extend from the cams to the hinged angle plate as described above, so that rotation of the cams in one direction produces closing movement of the angle plate against the side of the frame followed by upward movement of the carrier towards the locating surfaces.

The invention will now be described in more detail, by way of example, with reference to the accompanying drawings, in which:

FIGURE 1 is an exploded perspective view of apparatus for holding chromatographic plates in coplanar relationship while they are being coated, parts of the apparatus being broken away to expose internal details;

FIGURES 2a, 2b, 2c and 2d show successive stages in setting up the apparatus as viewed on the line and in the direction indicated by the arrows IIII in FIGURE 1; and

FIGURE 3 shows a detail of FIGURE 1.

Referring to FIGURES 1 and 3 the apparatus comprises a base frame 1 of rectangular shape and mounted on adjustable levelling feet 2 disposed beneath respective corners. An angle plate 3 forms one fixed side of the frame 1 and is of L-shaped cross-section, the upper portion of the upright limb of the L being slightly inclined inwardly over the horizontal limb of the angle plate and having a rib 4 adjacent its upper edge. The rib 4 has a flat undersurface 5 providing a non-yielding locating surface.

Six metal cross-bars 7 extend across the base frame 1 and each is bolted at one end into the angle plate 3. The cross-bars 7 are bolted near their other ends to respective positions on a horizontal limb 8 of an angle iron 10 having its vertical limb 10 extending downwardly beneath the apparatus to provide rigidity to that side of the base frame. The cross-bars 7 have terminal portions 11 which project beyond the angle iron 10. One cross-bar 7 is provided at each end of the base frame and has bolted to it an end-piece 12 formed as a channel lying on its side. The intermediate four cross-bars 7 have their upper surfaces each formed at each end with a step v13.

Journalled into the four intermediate cross-bars 7 is a shaft 14 extending through the central portion of the base frame 1. Two cams 15 are respectively fixed to opposite ends of the shaft 14 where such ends project beyond the second and fifth cross-bars 7. The third and fourth cross-bars 7 are relatively close together and a bevel gear 16 is fixed to the shaft 14 between them. A bridge piece 20 is fixed to the third and fourth crossbars 7 and carries a first journal block 21 between the two cross-bars. A second journal block 22 is screwed to the horizontal flange of the angle plate 3 and an operating spindle 24 rotatably supported by the journal blocks passes through their centres and through the upright limb of the angle plate 3. The spindle 24 carries a locating collar 25 between the two journal blocks 21, 22 and a second bevel gear 26 which meshes with the bevel gear 16. A handle 27 rotatable through 180 degrees is mounted on the outer-end of the spindle 24 which beyond the angle plate 3.

The angle iron 10 has hinged to it a movable second angle plate 30 which is identical in cross-section to the angle plate 3 and is similarly provided with a rib 31 having a flat under-surface 32 to provide a second locating surface. The terminal portions 11 of the cross-bars 7 project into the angle of the plate 30 so that they abut its upright limb when the plate 30 is moved from the position shown in FIGURE 2a to the position shown in FIGURE 2b. When the angle plate 30 is in the position shown in FIGURE 2b the under-surface 32 of the rib 31 is coplanar with the under-surface 5 of the rib 4.

The movable angle plate 30 is moved between its two positions by a connector shown in detail in FIGURE 3 and which connects the two cams 15 to the angle plate 30. Referring to this figure each connector comprises a rod 35 eccentrically pivoted at 39 to the cam 15. It will be particularly noticed that the pivot point on the cam 15 is adjacent to the face of the cam which is radially nearest the shaft 14. The other end of the rod 35 extends into one end of a sleeve 36, and through a compressible coil spring 37 mounted between a head 38 formed on the rod 35 and an inwardly-turned flange 40 formed on one end of the sleeve 36. If desired a Metalastic rubber bonded connector may be used instead. The other end of the sleeve 36 carries a diametrically-extending horizontal pivot pin 41 which also passes through an endportion 42 of reduced cross-section of a stud 43 which is screwed into the upright limb of the angle plate 30 adjacent its lower limb.

Glass plates 44 which may be differing thicknesses as shown in FIGURES 1 and 2 and which are to be coated in the apparatus are mounted side-by-side on a rectangular carrier 45 providing elongated support means and shaped to rest on the base frame 1 between the upper portions of the angle plates 3 and 30 beneath the ribs 4 and 31. The carrier 45 is of light rigid construction having its sides formed by angle members 46 which are strengthened by two cross-braces 47. The upper limbs of the angle members 46 are horizontal and the two longer angle members each carry a thick sponge rubber strip 48 on its upper surface. The strips 48 are approximately half an inch in height and a readily flexible plastic sheet 50 is cemented to the top surfaces of the strips 48 and covers the top of the carrier 45. Finger recesses 51 are formed in the strip 48 adjacent the movable angle plate 30 and sheet 50 to enable the plates to be easily lifted individually from the carrier after they have been coated.

The apparatus is used as follows:

The chromatographic plates 44 which are to be coated are placed side-by-side on the sheet 50 of the carrier 45. The thicknesses of the plates 44 may vary considerably so that they may appear much as shown in FIGURE 1.

The handle 27 is moved to the position shown in FIG- URE 1 so that the angle plate 30 is moved to the open position as shown in FIGURE 1. The spacing between the ribs 4 and 31 is now greater than the width of the carrier 45 so that the carrier can be lowered onto the frame so that the angle members 46 locate in the stepped portions 13 of the cross-bars 7. If one of the angle members does not quite locate in one of the steps it does not really matter as the apparatus, in use, is self-centering and the correct location of the angle plates in both recesses 13 will occur during operation of the handle, as is explained later. FIGURE 2a shows the apparatus :after the carrier has been placed in position and the angle plates 46 have located in the stepped portions 13. It will be seen from this figure that the under-surfaces of the two cross-braces 47 of the carrier rest respectively on the portions of the earns 15 adjacent the pivot connections 39 with the rods 35. It will also be seen that the top surfaces of the glass plates 44 are spaced beneath the undersurface 5 of the rib 4.

The handle 27 is now rotated upwardly. This movement is transmitted by way of the spindle 24 and bevel gearing 26, 16 to the shaft 14 and causes the cams 15 to rotate in a clockwise direction as shown in FIGURE 2. During the first 45 degrees of movement of the handle 27 the rotation of the cams 15 moves the rods 35 to the right, as viewed in FIGURE 2, so that the movable angle plate 30 is swung about its hinge to the closed position shown in FIGURE 2b where the angle plate 30 abuts the end-faces of the terminal portions 11 of the cross-bars 7. It will be noticed that each cam 15 is so shaped that no upward movement of the carrier 45 has occurred as yet. However, the angular rotation of the cam 15 slides the carrier 45 up against the upright limb of the angle plate 3 so that any misalignment of the glass plates 44, resulting in their corners projecting beyond the edges of the carrier 45, is corrected as the angle plate 46 is slid across the stepped portions 13 of the cross bars 7.

The rotation of the handle 27 is continued and the further rotation of the earns 15 is permitted by com pression of the coil spring 37 in the sleeves 36 despite no further movement of the angle plate 30 occurring. Referring to FIGURE 2c, this allows the rod 35 to move through the dead centre position with respect to the cam 15. As is clearly shown in FIGURE 2c the cams 15 have now started to lift the carrier 45 upwards so that the upper marginal edges of the plates 44 are moved towards the coplanar under-surfaces 5 and 32 of the ribs 3 and 31. During this movement occurring after the dead centre position the compression of the springs 37 holds the angle plate 30 firmly in position against the ends of the cross-bars 7.

During the final 90 degrees of movement of the handle 27 the cams 15 raise the carrier 45 so that the top surfaces of the plates 44 have the upper faces of their marginal end-poltions extending along the sides of the carrier 45 pressed resiliently but firmly against the undersurfaces of the ribs 4 and 31 by the sponge rubber strips 48. The plastics sheet 50 is flexibly deformable and the strips 48 resiliently yield to accommodate glass plates 44 of different thicknesses. As the under-surfaces 5 and 32 of the ribs 3 and 30 are non-yielding and coplanar the top surfaces of all of the glass plates 44 are coplanar also. A coating trough resting on the coplanar plate surfaces between the ribs 4 and 31 can then be slid down the length of the apparatus. A doctor blade at the trailing end of the trough meters the depth of the slurry coating deposited on the top surfaces of the plates so that the coating trough leaves behind it a uniformly thick layer of slurry, commonly 250a thick, on all the plates 44. When coating is completed the handle 27 is returned to its former position, as shown in FIGURE 1, and the coated plates may be individually lifted from the apparatus by inserting a finger in one of the finger recesses 51. Alternatively the carrier 45 together with the coated plates 44 may be lifted bodily from the apparatus.

The plastics sheet 50 has a smooth top surface and is readily cleaned so that the apparatus can be used for several coating operations in rapid succession. Also the sheet 50 prevents the slurry from dripping between plate junctions onto the operative parts of the apparatus.

From the above description it will be appreciated that the applicant has devised apparatus which is capable of holding chromatographic plates in coplanar relationship for coating, irrespective of their thicknesses. Also the apparatus is robust and simply constructed and is very conveniently loaded and unloaded. Additionally a single movement of a handle correctly positions the plates in the apparatus, moves the locating surfaces provided by the undersides of the ribs 4 into coplanar relationship, and finally lifts the plates and presses them into contact with the undersides of the ribs so that the upper surfaces of the plates 44 are held coplanar during coating.

It will be appreciated that various modifications of the apparatus may be made. For example, the bevel gearing connecting the spindle 24 to the shaft 14 may be replaced by pinion gears when it is desired to operate the mechanism from a handle at one end. The handle is suitably of rotary type and the spindle extends axially parallel to the shaft so that pinions carried by the spindle can mesh with gears carried by the shaft.

I claim:

1. Apparatus for holding chromatographic plates of different thicknesses side-by-side with their top surfaces in coplanar relationship, comprising: elongated support means onto which the plates to be coated are placed; resiliently yielding surfaces provided by said support means beneath opposite marginal edges of the plates; a base frame carrying the support means; spaced nonyielding locating surfaces connected to said base; means for producing relative movement of said non-yielding locating surfaces between first relative positions at which they lie in a common plane above respective marginal edges of the plates, to second relative positions at which the spacing between the non-yielding surfaces is greater than the spacing between said yielding surfaces; at mechanism operating to reduce the distance between said nonyielding surfaces and the marginal edges of the plates; and a handle operatively connected to said means and said mechanism and which by a single movement in one direction first moves the non-yielding locating surfaces from said second relative positions to said first relative positions and then reduces the distance between said non-yielding surfaces and said yielding surfaces whereby the marginal edges of the plates are gripped between them so that the top surfaces of the plate are brought to said common plane in readiness for the application of a coating thereto.

2. Apparatus as set forth in claim 1, in which said mechanism comprises lifting cams mounted in the frame and rotated by the handle to lift said yielding surface towards said non-yielding surfaces.

3. Apparatus as set forth in claim 1, in which said means include resilient connectors eccentrically connected at one end to a shaft rotated by a handle and at the other end to a part integral with one of said non-yielding surfaces and hinged to the base.

4. Apparatus for holding chromatographic plates of different thicknesses side-by-side with their top surfaces in coplanar relationship, comprising: elongated support means onto which the plates to be coated are placed; resiliently yielding surfaces provided by said support means beneath opposite marginal edges of the plates; a base frame carrying the support means; spaced non-yielding locating surfaces connected to the base; means for producing relative movement of said non-yielding locating surfaces between first relative positions at which they lie in a common plane above respective marginal edges of the plates, to second relative positions at which the spacing between the non-yielding surfaces is greater than the spacing between said yielding su-rfaces; a mechanism operable to lift the yielding surfaces towards the non-yielding surfaces; and a handle operatively connected through gearing to said means and said mechanism and which by a single movement in one direction first moves the non-yielding locating surfaces from said second relative positions to said first relative positions and then lifts said yielding surfaces towards said non-yielding surfaces to grip the marginal edges of the plates therebetween so that the top surfaces of the plates are brought to said common plane in readiness for the application of a coating thereto.

5. Apparatus as set forth in claim 4, in which said mechanism comprises lifting cams mounted in the frame, and said support means comprises a carrier resting in the frame on the cams and having said resiliently yielding surfaces formed on its opposite longer sides.

6. Apparatus as set forth in claim 4, in which said support means comprise a carrier bodily removable from a recess in the frame and having spongy strips extending along the upper surfaces of its longer sides and providing resiliently yielding surfaces which are spanned by an impervious flexible sheet.

7. Apparatus for holding chromatographic plates of different thicknesses side-by-side with their top surfaces in coplanar relationship, comprising: an elongated carrier onto which the plates to be coated are placed; resiliently yielding surfaces provided on opposite longer sides of the carrier beneath opposite marginal edges of the plates; a base frame having a recess in which the carrier is mounted; two side walls connected to said base, One side wall being fixed rigidly thereto and the other being hinged to the base about an axis extending parallel to said resiliently yielding surfaces; a non-yielding locating surface provided on each side wall; means for moving the hinged side wall between a first position at which the non-yielding locating surface formed thereon lies in the same plane as the other non-yielding locating surface, the two locating surfaces being disposed respectively above opposite marginal edges of the plate, to a second position at which the hinged side wall is swung away from the other side wall so that the spacing between said non-yielding surfaces is greater than the spacing between said yielding surfaces; a mechanism operable to lift the carrier so that the yielding surfaces move towards respective non-yielding surfaces when in said one position; and a handle operatively connected to said means and said mechanism and which during the initial part of a single movement in one direction moves the hinged side wall from said second position to said first position and then during further movement lifts the carrier so that the marginal edges of the plates are gripped between said yielding surfaces and said non-yielding surfaces thereby bringing the top surfaces of the plates to said common plane in readiness for the application of a coating thereto.

8. Apparatus as set forth in claim 7, in which said handle is disposed alongside the fixed side wall of the frame and a spindle transmits movement of said handle through bevel gearing to a shaft mounted in the frame parallel to said side walls and carrying at each end a lifting cam surface which engages the underside of the carrier and has eccentrically pivoted thereto a resilient connector joined at its other end to the hinged side wall.

9. Apparatus as set forth in claim 7, in which the handle is mounted at one end of the frame and gearing transmits its rotational movement to an axially parallel shaft in the frame having at each end a carrier-lifting cam to an eccentric position on which is connected one end of a resilient connector having its other end connected to the hinged side wall.

10. Apparatus for holding chromatographic plates of different thicknesses side-by-side with their top surfaces in coplanar relationship, comprising a rectangular base frame having feet at its corners; a fixed side wall extending along one longer side of the base frame; a movable side wall extending along the other longer side of the base frame and hinged thereto for movement between a first position at which it is parallel to said fixed side wall and a second position at 'which it is swung away from said fixed side wall; locating surfaces formed on said two side walls and 'which, when the hinged side wall is in said one position, overlie opposite longer sides of the frame in coplanar relationship; a shaft extending through the central portion of said base frame and parallel to said side walls; a cam mounted at each end of said shaft; two resilient connectors respectively pivoted to eccentric positions on the remote faces of said cams and joined at their other ends to said hinged side wall at spaced positions along its length; a spindle projecting from the frame; a handle mounted on the projecting end of the spindle; gearing inter-connecting said spindle and said shaft for transmitting motions therebetween; a rectangular carrier framework dimensioned to fit between said side walls and beneath the locating surfaces when said hinged side wall is in said first position; a resilient spongy strip extending along each of the upper surfaces of opposite longer sides of said carrier directly beneath the positions of said locating surfaces; and an impervious flexible sheet covering the strips and spanning across the carrier framework.

11. Apparatus as set forth in claim 10, in which the carrier is bodily removablbe from the frame when said hinged side wall is in said second position.

12. Apparatus as set forth in claim 10, in which one of said strips disposed adjacent to the hinged side wall is formed with spaced finger recesses.

13. Apparatus as set forth in claim 10, in which each. of the resilient connectors comprise a spring mounted between a piston and a cylinder, inside the cylinder.

References Cited UNITED STATES PATENTS 1,075,913 10/1913 Hirschberg et al.

1,146,974 7/1915 Sweigard --76 2,284,972 6/1942 Carson 269-153 X 2,475,475 7/1949 Butter-worth 269-153 X 2,568,905 9/1951 Wiehsner 269--239 X 2,581,040 1/1952 Mullen'bach 269154 3,084,930 4/1963 Wilcox 269-239 3,284,962 11/1966 Hott et al 269310 X FOREIGN PATENTS 869,257 3/1953 Germany. 1,015,697 10/ 1964 Great Britain.

MORRIS KAPLAN, Primary Examiner. 

